Breech-closure



0. B. GRAHAM. BREECH CLO.SUR.E.' APPLICATION mm Nov; 26. 1917.

Patented May 25,1920.

- To all whom it M a Martini:

un 'rslo srarss jeareiar oer-ice.

OLI ER IB. GRAHAM, or CLEVELAND. onto], ASSIGNOR, BY'I-M'ESN'E-ASSIGNMENTS, TOw

AUTO-ORDHANCE OOBPQRATION, ORNEW YORK, N. Y., A CORPORATION or NEW Be it known that 1.()LI.'ER l3. GrRAiHAM,

a citizen of the tinted States of America,

and, resident of Cleveland, in the county of Cuyahoga and State of Ohio, have invented ,jnew' and useful Improvements in Breech- (Flosures.

I of which the following is a specii cation. 'i y This invention relates to breech closure mechanism for firearms and more particularly to breech closures of the type disclosed in the application of Eiclrhoti, and Payne, Sr. X0. 203,981.filedB oveniber 26,1917.

Breech closures of the type referred to I comprise three essential elements, i'iame'l'y,-ahreech-block, a stop or abutment, and, a

lock arranged to be interposed between the...

breech-block and stop to lo'clcthe block against breech pressures of relatively large magnitude and to be moved from between the breech-block and stop automatically by i diminished breech pressure of' sucli-magiii .t-iide as safely to retract/the-bieech-block.

Breechelosures of this type operate accord- I ing to the principle set forth in the patentto Blish,l,13l,3l9, granted March 9, .1915.

- and I hereby makereference to this 'patent for a more detailed disclosure of the princ'iple underlying the mode of operation of I breech closures of the type to which my. in-

vention is particularly applicable. It is not' to .be understood inlthis connection. however, that my improvements are limited iii application to mechanisms embodying this principle.

According to the aforesaid applicationthe .saidi three essential elements comprise a'reciprocatory bolt, a guideway having atransverse surface forming a stop, and alock movable both longitudinally with the bolt and laterally with respect 'tothe bolt, the lateral .movement carrying the lockto andfrom 'locking position between the bolt and the stop; and my improvements are parto move the locking member of the breech ticularly thou h not eXclusivelv' applicable closure -mechanism into locking position quickly. smoothly and positively, to move the locking member both to and trom the -..,iiring chamber with the breech-block and Specification of Letters Patent.

BREE'oH-oLosU'BE.

also angularly or transversely or otherwiselaterally. with respect to the breech-blockin' a simple and efficient manner, to actuate the breech-block and locking member. by com-,

nion means adapted to move thebreechblock relatively to the firing chamber and also forcibly to move the locking member relatively to the breech-block, to, efiectthe ber during the longitudinal movement of the breech-block, and more particularly" to attain these resiiltsiii breech mechanism of.

the aforesaid type.

parent from the following description and the accompanyingdrawings,- in which,

"Figure l is a sectional 'perspective view of a portion-of'a firearm adapted .to use my. mprovedv breech closure ,60 transverse movement of the locking mem Other objects of the invent-'ioni'will bejap- Fig. 2' is a perspective view of a n emf. ho'diment of 'niv improved breech closure,

a-dapted to the'firearm of Fi 1; l y Fig. 3 is a view similar to Fig- 1 of a' mod1fied construction; and

at is a view similar to Fig.2 show ing a modification of my improved closure adapted to thefirearni of-Eig. .3. The embodiment of my improved breech closure-mechanism illustrated in F 1g. 2

comprises a bolt, B adapted to reciprocate longitudinally oft-he receiving; chamber off a firearm, suchias illustrated for example in Fig. 1, wherein the receiving-chamber is indicated at 10 in the-rear of'the barrel l1 'cont aiiiing the firing chamber 12. .The bolt B is provided with a stem 1 of reduced cross-sectional area extending 'rearwardly' therefrom, and surrounding this stem is a follower in the. form of a sleeve 2 adapted to slide-longitudinally of the stem :1. Be-' tween the forward end of the bolt and the sleeve 2- is disposed a locking member'IJ. the locking member having a U-shaped crosssectional shape and extending over the stem of the bolt so 'as to engage the rear faces 3 of the bolt B at its forward end and to engage the forward faces 4 of 'the sleeve ,2 at its rearward end. Lugs 5 project laterally from the opposite sides of the locking member L and thereceiver "10 is provided with a slot- 6 to receive the lugs 5 and guide the movement of the locking member. The

.slot 6 is provided with a lateral portion 7 spond with the inclination of the forward and rearward surfaces of the lugs 5. The abutting surfaces of the breech-block B and locking member L may be inclined relatively to the path of movement of the bolt any desired degree, but the inclination of these surfaces must bear a certain relationship to the slope of the forward and rearward faces of the lugs 5 and the forward portion 7 of the slot 6, the difference in inclination between these surfaces being approximately 5 for the standard U.- S. service rifle, all

as more fully explained in the aforesaid application. In the rear of the sleeve 2 is provided a compression spring 8, this spring abuttingagainst asuitable stop at its rearward end and pressing forwardly against the rear end of the sleeve 2.

According to the present invention the abutting surfaces between the locking member L and the follower 2 are inclined relatively to the path of movement of the bolt B, the inclination relatively to a vertical transverse plane being opposite to that of the abutting surfaces between the locking member and the breecl1block, the object of inclining the abutting surfaces of the looking member and follower being apparent from the following description of the operation of the mechanism.

When the bolt B is in forward position closing the firing chamber 12, the locking member L is disposed in uppermost position as illustrated in Fig. 2, the lugs 5 being disposed in the oblique forward portion 7 of the slot 6 with the rear faces of the lugs 5 abutting against therear faces S of the oblique portions of the slots, which constitute stops adapted to hold movement when the firearm is dlscharged,

the breech pressure being transmitted to the stops S through the forward end of the" bolt and the locking member L. The rearward thrust on the bolt B produced by a discharge in the firing chamber F tends to force the locking member L upwardly "by virtue of the inclination of the abutting faces of the two members, and it ing member downwardly by virtue of the mclination of the abutting surfaces of the lugs 5 and stops S. Owing to the fact that the inclination of the lock-stop surfaces is greater than the inclination ofthe lock-block surfaces there is a resultant force acting downwardly on the lock tending to, force it downwarily along the oblique portion of the slot. However, the difference of inclination between the two sets of surfaces is such that high breech pressures lock the parts togetherso that the locking member cannot the bolt B against rearward tends to force the lock- Y slide along the slot 7, whereas breech pressures of diminished magnitude are effective to force the looking member along the slot 7 according to the principle disclosed in the aforesaid patent, as is more fully described in the aforesaid application. When the lugs 5 come into alinement with the longitudinal portion of the slot the bolt lock and sleeve move rearwardly together against/the action of the spring 8. a

The above operation is substantially "the same as disclosed in the aforesaid application, but during the forward movement of the parts the operation. is different. After the parts have been fully retracted as above described, the spring 8 becomes effectivetto advance the parts into locking position. So long as the lugs remain in the longitudinal I portions of the slots 6, the parts move forward as a unit with no relative movement therebetween. However, when the lugs 5 reach the oblique portions of the slot, the locking member moves obliquely with relation to the path of movement of the bolt during the completion of the forward movement of the bolt. By virtue of the fact that the abutting surfaces of the locking mem her and follower arejinclined .upwardly and rearwardly, the forward pressure on the fol lower 2 tends to force the locking member upwardly so that when the lugs 5 reach the lateral portions of the slots 7 this upward pressure becomes effective quickly and positively to move the locking member transversely with respect to the bolt. in this 'way the locking member is given an' upward zontal portion of the slot and an instant before the forward faces of the lugs engage the forward sides of the slot 7 so that there is. substantially no shock of impact caused by the lugs 5 engaging the forward faces of the slots 7 i tween the sleeve and lockingmember be made sufficiently great the lugs, 5 may neverengage the forward faces of the slots 7, in which event the forward faces of the slots 7 serve no purpose'in the-normal operation of the mechanism. y

It will be observed that during the, forward movement of the parts the locking member begins to move .transversely of the bolt "into locking position before the bolt reachesadvanced position, thus if a premature discharge is produced by the advancement of the bolt, the locking member will have reached its locking position before the premature--;discharge takes place and will therefore lock'the parts in position until the pressure drops to the predetermined value, thereby preventing the parts being shot rearwardly with excessive force.

In Figs. 3 and l I have shown a modification of my: improved mechanism for the Indeed, if the inclination bepurpose of illustrating the fact that the inclination' of the various sets of abutting surfaces may be widely varied within the scope of the present invention. The parts in Figs. land 4 are designated correspondingly to the parts of Figs; 1 and 2, and the parts are constructed and arranged the .same except that the bolt-lock surfaces are vertical,

"the lock-stop surfaces are nearly vertical,

and the lock-sleeve surfaces HIGilIlCllllGCl a greater amount than in 11g; 2.

bolt-lock surfaces and loclr'stop surfaces are j lon'git t Fig; 2 the lock-sleeve surfaces are refer-- c 7, ably inclined a greater amount so that when the lugs reach the forward end of the ainal portions of the. slots during the forward movement of the parts, the upward tendency on-thel lock produced by the slopingf lock-folloiver surf-aces will be greater, tl1ereby "procluci'ng a morerapid upward movement o'fthe-lock, relatively to the bolt.

his is desirable to prevent an impact bef 'tween thelugs 5 and the forward faces of the application of Eickhoif, filecPMa'rch 20,1918,- or other suitable the slots 7 f inasmuch as theloek must'com pleteits lateral movement .;while the bolt ,is'

moving'a shorter distance than when the slots 7 have a greater slope as in P 1g. 1;

X'Vhile no firing pin has been illustrated in the drawings in'asmuehl as it formsno part of the present invention'it is to be under'- stood that a1firing pin 'could be employed in the manner illustrated-in the aforesaid application of ,Eickhoff l Sr. No. 228,657,

manner.

I claim:' l; Breech closure mechan sm for firearms comprising a bolt. a lock. a follower, and a 'l'QCOll spring. the lock being movable laterally of .the bolt into'locked position in front of locking abutments on the receiver and being movable longitudinally with the bolt when out of locked pesition. the lockhaving bearing surfaces engaging the bolt. re-

ceivei and follower respectively, certain of said engaging surfaces including the lockfollower surfaces being-inclined to the hue of breech pressure at such angles that the movement of the lock into and out of locked.

position is controlled by the breech and recoll pressures acting upon the lock respectivelythrough the bolt and follower.

.9.-Bre ech closure mechanism for firearms comprising a bolt, a lock, a follower, and a 'hile the.

ayhe. ,or in recoil spring, the lock being movable later-j ally of the bolt into locked position in front the lock andthence to the receiver, and said loclr follower surfacesbeing inclined inthe opposite direction relatively to said lockreceiver surfaces at such angles that the lock is automatically locked in response to the recoil spring actingon the follower. 3. Breech closure mechanism for firearms comprising a bolt,a 'loc'k,-=a follower and. a recoil spring, the loch' havingi oblique surfaces adapted to bearagainst oblique abutmerits on the-receiver to lock the bolt closed, said surfaces being in clinedrelatively to the vline of breechpressure at such angles that-the bolt is maintained closed during high breech pressure but is automatically 3 opened directly iii-response. to the breech pressure acted thereon when the pressure has decreased to a relatively low value, a d,-

saidlock and follower. having oblique .gagihg surfaces inclined in thenspposite (ii-- freech presj sure to move the look into locked positlon rection relatively to the .line of in response to the-recoil spring, whereby the block. the surfacesof lock-block'contact and lo'clestop contact being disposed at an angle fl with each other such-as to lock the breech block during high breech pressures and to release. it for movement 111 response to low breech pressures.- a follower in sliding engagement with the locln yielding means operativeon the follower to urge the lock and block to breech-closure position. the lockfollc ver surfaces being inclined with relation to the lock-stop surfaces, to urge the lock into the stop.

5. Breech closure for firearms, comprising a breech-block. a lock. and a stop. the lock being movableon the stop laterally of the block. the surfaces of lock-block contact and lock stop .contact being inclined to the line of breech pressure and at an angle with each other such as to lock the block during high breech pressures and to release it for movement under low breech pressures. a

.guide substantially parallel with the line unlocking and'locking movements of the look i (if hiteech pressure from which the stop is dev'elepedto its angle withjthe said line, a follower in sliding engagement with the lock and carried by the bLf ek, yielding 5*"ihetns operative on the followei t0 urge the -:leck] along the Way and inte the stop and thereby move the block to i ia'reech closing position, the leek-follower surfaces being inclined with relation to the stop-surface to urge the look from the Way into the stop. 10

Signed by me at Cleveland, Ohio, thisllth day of November, 1917.

OLIVER GRAHAM; 

